Agricultural sweeps are employed as earthworking tools in the cultivation of soil. A typical sweep comprises a stem portion which is removably mounted on the tine of an agricultural tillage implement and an earthworking portion attached to the stem which is pulled through the soil. The earthworking portion typically has an arrowhead shape and comprises a pair of symmetrical wing elements extending rearwardly from a point. An example of an agricultural sweep is described in U.S. Pat. No. 5,979,568, issued Nov. 9, 1999 to Parish.
In the past, agricultural sweeps were typically attached to tillage implements by bolting the stem of the sweep to a tine of the implement, either directly or through an adaptor attached to the tine. Removal of the sweep therefore required the use of wrenches or the like to loosen and/or remove the bolts from the stem of the sweep. As a typical tillage implement would utilize a number of such sweeps, the labor involved in mounting and dismounting such sweeps from the implement was considerable.
To overcome these difficulties, knock-on sweeps were developed in which the adaptor or the tine itself is tapered to be complementary with a tapered stem of the sweep. This type of sweep is mounted by striking the tip of the sweep with a hammer to firmly wedge the stem of the sweep over the adaptor or tine. The sweep can then be dismounted by a hammer blow applied at the rear edge of the stem. An example of a knock-on sweep is described in U.S. Pat. No. 5,711,378, issued Jan. 27, 1998 to Yeager.
Due to their ease of installation and removal, knock-on sweeps have become popular and are now widely used by farmers. However, knock-on sweeps are not free from disadvantages. The primary disadvantage with such sweeps is that the frictional grip between the sweep and the adaptor or tine is subject to failure, resulting in accidental release of the sweep.
To address this problem, many currently available knock-on sweeps, including that disclosed by the above-mentioned Yeager patent, utilize retaining devices to prevent accidental release of the sweep while attempting to preserve the simplified mounting and dismounting feature of knock-on sweeps. The retaining device of Yeager comprises an adaptor onto which the stem of the sweep is wedged in a normal working position. The adaptor has a transverse groove which aligns with rectangular cutouts in the stem of the sweep in the normal working position. A pin is then inserted into the groove and through the cutouts to retain the sweep against accidental release. The pin is also retained against accidental release by a pair of resilient flat springs bolted to the adaptor.
One problem with presently-used retaining devices is that they consist of a number of parts, each of which may be prone to failure under the harsh conditions under which agricultural implements are used. A need therefore exists for a simplified retaining device for securing an earthworking tool to a tillage implement.